Lifter rise at TDC

[RAS]

Hello Friends,
Rather than going through the center lining of the camshaft and degreeing it in, I'm wondering if there is a formula to determine the lifter rise on number one intake when the cylinder is at TDC. I called and asked my cam grinder and got my life threatened. No response. Some grinders give this information, but most don't. I'm just wondering, I know there is math to determine this I just can't find it. Anyone have any ideas?

[allencr267]

No maths with individual designs i'd think.
Some aren't symmetrical, finding the center between the same lift on the up & down ramps usually works easy.
Good luck.

[HQM383]

Hello Friends,
Rather than going through the center lining of the camshaft and degreeing it in, I'm wondering if there is a formula to determine the lifter rise on number one intake when the cylinder is at TDC. I called and asked my cam grinder and got my life threatened. No response. Some grinders give this information, but most don't. I'm just wondering, I know there is math to determine this I just can't find it. Anyone have any ideas?

Interesting your cam grinder wasn’t open to forwarding that info. A few of the local grinders down here in Aus readily gave that info and even suggested using it to dial in. Below is an old cam card I found from a local grinder. The Comp Cams card doesn’t have that spec, at least not the cards I have but they do have the grind number that can be found in their lobe catalog. Their lobe catalog has ‘Tappet lift at TDC’ for 106* and 110*. Browse through that catalog that’s readily available online and you will see how much those figures vary with similar duration lobes and that makes me think there would not be an accurate, simple mathematical way to determine tappet lift at tdc with basic cam specs. If seat to max lobe lift was always linear there may be a formula but lift rates are always varied with lobe design. Hey, if I’m wrong then great, we’ll have a formula to work with. But I feel it would be quite complex.

[Nut124]

There is no formula. Need to know the actual cam C/L and the TDC lift value that correlates to the C/L.

[F-BIRD'88]

Is it farther to Cleveland, or by bus?

[rebelrouser]

Hello Friends,
Rather than going through the center lining of the camshaft and degreeing it in, I'm wondering if there is a formula to determine the lifter rise on number one intake when the cylinder is at TDC. I called and asked my cam grinder and got my life threatened. No response. Some grinders give this information, but most don't. I'm just wondering, I know there is math to determine this I just can't find it. Anyone have any ideas?

TDC ready to fire, there is no lift. TDC on the overlap if the cam is installed on center line both lifters should be at the same height, if cam is advanced the intake lifter is higher if retarded the exhaust is higher. I always look at this when I have an engine without an adjustable cam gear, just as a quick check, on a mild cam. If I have adjustable cam gears, or it is a bigger race type camshaft then I degree it. I never trusted a single lift measurement to see where the cam is installed, as many times I have gotten the wrong grind. Seldom anymore is the cam very far off from the card, if it is the grind listed on the card.

[CamKing]

No formula, but if your cam supplier won't give you that info, they shouldn't be in the cam business.
I just got off the phone, selling a customer a new custom cam. Before I finished writing up the invoice, I gave him the lifts at TDC and 10 degrees from TDC, so he could have the pistons cut.
It takes me 20 seconds to pull up the lift tables for the lobes, to get the lifter lift at any point.

[In-Tech]

Hello Friends,
Rather than going through the center lining of the camshaft and degreeing it in, I'm wondering if there is a formula to determine the lifter rise on number one intake when the cylinder is at TDC. I called and asked my cam grinder and got my life threatened. No response. Some grinders give this information, but most don't. I'm just wondering, I know there is math to determine this I just can't find it. Anyone have any ideas?

TDC ready to fire, there is no lift. TDC on the overlap if the cam is installed on center line both lifters should be at the same height, if cam is advanced the intake lifter is higher if retarded the exhaust is higher. I always look at this when I have an engine without an adjustable cam gear, just as a quick check, on a mild cam. If I have adjustable cam gears, or it is a bigger race type camshaft then I degree it. I never trusted a single lift measurement to see where the cam is installed, as many times I have gotten the wrong grind. Seldom anymore is the cam very far off from the card, if it is the grind listed on the card.

As stated, lift on compression stroke at tdc should be zero tappet lift, lift at overlap cycle and "split the overlap" was a quick and dirty, easy way, to degree a cam in the field within a couple degrees. Now, with asymmetrical lobes, degree a cam by intake lobe center(I use .005" from tdc of lobe) is my preferred method after I have verified the cam was ground correctly(shit happens, miss-boxed, bad day, friday, etc etc, rare but it does)

The mathematical version of an asymmetrical cam card can be off by a few degrees at lash and at .050" lifter rise unless the cam designer has fixed the cam card for accuracy, most do not. A symmetrical cam is (whatever lobe and duration event you are trying to measure) intake duration/2-ICL=IVO (ICL = Intake centerline, IVO = Intake valve opening)asymmetrical is whatever the fack because of changes in the ramps.

Anyway, if your cam card does the math symmetrically you can easily check that on paper or with a calculator. When that doesn't match what the cam is actually doing, chances are you are dealing with asymmetric lobes.

[F-BIRD'88]

You need to use the .050" lifter rise events as stated on the cam card to dial in your cam. On MANY cams this is expressed as if "straight up" cam phasing and it is thus UP TO YOU to then (check and) phase the camshaft ± to get it in the right-best installed position. "advance". (or retard)
Your cam grinder can advise, how much, if you need help.
As a default most cams for the popular legacy pushrod V8's most of us deal with run best overall with a bit of "advance" dialed in. 4° to 6° is typical. But do not assume your cam was ground with this dialed in already.
If you want it installed correctly use the .050" lifter rise events method.

[Walter R. Malik]

The "Performance Trends" camshaft analyzer gives that information when doctoring.

[In-Tech]

You need to use the .050" lifter rise events as stated on the cam card to dial in your cam. On MANY cams this is expressed as if "straight up" cam phasing and it is thus UP TO YOU to then (check and) phase the camshaft ± to get it in the right-best installed position. "advance". (or retard)
Your cam grinder can advise, how much, if you need help.
As a default most cams for the popular legacy pushrod V8's most of us deal with run best overall with a bit of "advance" dialed in. 4° to 6° is typical. But do not assume your cam was ground with this dialed in already.
If you want it installed correctly use the .050" lifter rise events method.

Oy vey can you read? I will re-state...what if the cam card was written WRONG straight from the guys who made it???? 99% of all cam cards are wrong!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[F-BIRD'88]

You need to use the .050" lifter rise events as stated on the cam card to dial in your cam. On MANY cams this is expressed as if "straight up" cam phasing and it is thus UP TO YOU to then (check and) phase the camshaft ± to get it in the right-best installed position. "advance". (or retard)
Your cam grinder can advise, how much, if you need help.
As a default most cams for the popular legacy pushrod V8's most of us deal with run best overall with a bit of "advance" dialed in. 4° to 6° is typical. But do not assume your cam was ground with this dialed in already.
If you want it installed correctly use the .050" lifter rise events method.

Oy vey can you read? I will re-state...what if the cam card was written WRONG straight from the guys who made it???? 99% of all cam cards are wrong!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Only some are.. Thats why you degree the cam in using .050" lifter rise method. Then you can then accuratly adjust the phasing as required.

Ya some use slight number rounding on the actual open close events. You'll see that when you degree it.
Its not rocket science.

You need not make this harder than it needs to be.

[6sally6]

Great you gave us the name of the cam grinder!!! Now........we get to deal with the clown.
Somebody that has that kind of attitude needs to be made public. Plenty of other grinders(like Mike) who give that 'little bit extra' to his customers that we can buy from.
Give out the name or....were you just bitch 'in?
6sally6

[RAS]

Full disclosure. The cam company I was referring to was Howards Cams. Now I went on you tube to C.O.M.E. racings engine assembly video dated 3-8-12. With the piston at TDC the lifter was .047-.048 of rise. With an indicator on the piston and lifter. The gents said that .003" was equal to 1 degree. I wanted to know because on an LS3 there is no timing pointer but if I knew the lifter rise at TDC I could always check that way. I'm coming off the dyno in about 2 weeks, so I'll play with it then. I have dial indicators etc. Thanks everyone for the comments. Boy, I miss Harold Brookshire.

[blown265]

Just adding to HQM383s experience- here's the cam in my personal engine ground 16 years ago by SureCams (an Australian cam company).
It shows, and they recommended, dialling the cam in using the inlet lobe lift at TDC on the overlap (in this case 0.080 thou)
They also provided other relavant cam events on the second page, so if a small(?) cam company can do it, the mainstream grinders should be able to as well.
Regards
Paulie